1. Field of the Invention
The invention relates to a regulating valve for adjusting the flow in an infusion or transfusion procedure, and more particularly to a regulating valve having selectable known flow rates.
2. Prior Art
A valve of this kind is known from DE 83 12 029 U. This regulating valve has a cup-shaped housing with an inlet connecting piece and an outlet connecting piece, which open into a hollow cylindrical valve chamber, and a rotating piece with a cup-shaped foundation and, at a distance therefrom, a cylindrical valve plug which can be inserted into the valve chamber to form a seal at the outside and has, on its outer periphery, at least one groove opposite the connecting piece which connects the connecting pieces in terms of flow and which has a cross-section changing in the peripheral direction.
A similar regulating valve is described in DE 43 40 191 C1. In order to limit the rotation of the rotating element here, complementary stops are provided on the base of the cup-shaped housing and on the base of the cup-shaped rotating element.
DE 42 01 416 A1 has a rotating element with two annular grooves offset from each other in the axial direction and connected with each other by means of a channel running axially. Therefore, the inlet connecting piece and the outlet connecting piece can be offset from one another in the axial direction.
A further similar regulating valve is described in DE 35 90 339 C2. Here, the face of a cylindrical rotating element has a groove which widens in the peripheral direction and inlet and outlet connecting pieces opening into the base of a cup-shaped housing. The condition for satisfactory functioning here is a sealing contact between the base of the housing and the face of the rotating element because it would be possible otherwise for a flow connection between the inlet and outlet connecting pieces outside the groove.
JP 2002035123 A shows a calculating disc for calculating the flow rate in a drip infusion. A number of scales are located on concentric circles on a flat plate. A rotating disc above the latter has a number of windows which are shaped like segments of a circle and through which the scales can be viewed.
The flow rate in such regulating valves depends not only on the effective cross-section, but also on the hydrostatic pressure. The container with the infusion fluid is usually fastened to an infusion stand, the container being mounted on the stand at a prescribed height. One customary height is, for example, 50 cm above the infusion point on the patient. A change in this height also leads to a change in the drip rate.
It would be desirable for hospital personnel if they could obtain information about the drip rate as a function of the hydrostatic pressure and as a function of the rotational position of the rotating element in a way that the effect of a change in the hydrostatic pressure, that is, the height of the container, can be estimated even before there is a change in the height. In addition, the regulating valve should be simple with respect to structure and mounting, simple meaning operable with one hand and making it possible to have a precise adjustment of the flow rate. Furthermore, with the present flow regulating valves, a common limitation is that the flow rates are accurate for low viscosity fluids, such as saline solutions. Saline (isotonic salt) solutions, typically with low viscosities, are nominally used to calibrate regulating valves, and thusly commonly do not have good correlation with fluids of higher viscosity. When regulating fluids having higher viscosity, the usual scales are not applicable, and in fact may be misleading to the point of having serious negative consequences. Therefore, it would be advantageous for the user to have a scale or markings showing the flow rates for fluids having a higher viscosity. Accordingly, what is needed is an invention comprising a first standard scale for isotonic salt solutions, wherein said invention can be cross-referenced to indicia of fluids having a higher viscosity. The cross-reference can refer to empirical results in a manual or digital library or to a mathematical algorithm.